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FactCheck: Yes, masks, including cloth masks, can help prevent Covid-19 transmission

Studies have shown that masks can help prevent the spread of the virus.

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A NUMBER OF claims on social media have suggested that face masks are not effective against Covid-19.

Some social media users have said that masks do not work or aren’t safe, while one post has claimed that there have been no studies on the “protective value of repeat wearing of dirty, contaminated cloth masks”.

However, claims that masks are ineffective or unsafe are not supported by trusted scientific evidence nor by public health bodies which have recommended their use to curb the spread of Covid-19.

The Claim

Multiple claims have appeared on social media in recent months arguing that masks are ineffective.

One post on an Irish Facebook page from December wrote: “It’s a con the world’s biggest con and most people wear them knowing they don’t work only afraid of what people will say to you.”

Another Facebook post that made several false claims said that people “continue to promote masks as safe and effective, despite ample sources for and against” and that “even now [people] don’t want to know about the risks associated with mask-wearing.”

The post has been seen over 63,000 times since it was first posted on 17 October.

On 28 December, a Twitter user tweeted: “What is the protective value of repeat wearing of dirty, contaminated, cloth masks? No study has ever been done on this real world question. Even in perfect sterile conditions, surgical grade masks are quickly contaminated with viral particles and should be replaced.” 

The tweet was originally posted on Twitter on 28 December and has since been screenshotted and shared elsewhere on social media.

Tweet claim dirty masks A tweet shared on 28 December

The Evidence 

The World Health Organization, the Centres for Disease Control and Prevention (CDC) in the US, and the Health Service Executive (HSE) – as well as other bodies around the world – recommend the use of masks to help curb the spread of the virus.

There is widespread scientific evidence to show that masks can help to reduce the spread of infections, and in the last year, a range of studies have been carried out on masks’ effectiveness against Covid-19. 

The virus spreads between people from an infected person’s mouth or nose in “small liquid particles when they cough, sneeze, speak, sing, or breathe heavily”, according to the WHO.

“Other people can catch Covid-19 when the virus gets into their mouth, nose or eyes, which is more likely to happen when people are in direct or close contact (less than one metre apart) with an infected person.”

Masks, including cloth masks, work by reducing the spread of droplets that spread a virus, mostly by blocking particles that a person wearing a mask exhales, but they can also reduce the droplets that a person wearing a mask inhales by filtering droplets and particles.

One social media user asked what the “protective value [is] of repeat wearing of dirty, contaminated, cloth masks” – but it is not recommended to wear a dirty or contaminated mask in the first place.

Public health guidance advises that cloth masks should be washed frequently with soap and hot water.

There has been scientific research carried out into the efficacy of cloth masks and how to decontaminate them between uses, particularly in the past year as their usage has grown massively. 

A study published in September 2020 tested different types of common disposable masks and cloth masks, especially ones from common fabrics that could be used if there was a shortage of other masks, like surgical masks.

It recommended that cloth masks which have multiple layers and use a blend of different fabrics are the most effective, particularly ones which have an inner layer of cotton or linen, a blended middle layer, and an outer layer of polyester or nylon.

Cloth masks that are being reused should be washed daily in soap and water heated to at least 60 degrees Celsius, the study said.

“While cloth face coverings may not be as protective as surgical masks or respirators, an optimal quality cloth mask can be designed by an understanding of the principles of design and the differences between filter mediums, construction, mechanisms of action of different fabrics, key performance factors and limitations in these common masks,” it said.

“Formal guidance of design principles for cloth masks should be provided by governments where cloth masks are recommended.

“Mask wearing in the general population with a well-designed cloth mask can flatten the curve in areas of high incidence and should be used in combination with other non-pharmaceutical options such as social distancing and hand hygiene,” it concluded.

Another study, which was published in October 2020, outlines that cloth masks are not the optimal mask type for healthcare workers, who should ideally use a medical or surgical mask, but that they are useful in a community setting to prevent the spread of infection.

“Protection [given by cloth masks] is affected by proper mask use as well as by selection of fabric and design of the masks for water resistance, filtration, and fit,” the study said.

“Current evidence suggests that multilayered masks with water-resistant fabric, high number of threads, and finer weave may be more protective,” it said.

The study said that cloth masks “can be reused after being decontaminated by various techniques, ideally washing in hot water with soap”.

“Other methods or products include using bleach, isopropyl alcohol, or hydrogen peroxide; autoclaving or microwaving; and application of ultraviolet radiation or dry heat.

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“Unlike disposable medical masks and respirators, the material of cloth masks is unlikely to degrade from standard decontamination procedures.”

Researchers have noted that more studies should be done on different types of cloth masks and their efficiency, but that current evidence does show they have value for preventing the transmission of infection.  

At the start of the pandemic, some scientists did have questions about how effective masks would turn out to be against the virus, but as time went on, it became clear that they were helping to curb the spread.

TheJournal.ie has previously debunked claims around the safety of masks, including the suggestions that:

  • Spikes in Covid-19 infections were actually Legionnaire’s disease caused by mask-wearing: FALSE
  • Masks reduce oxygen intake: FALSE
  • Masks are dangerous harbours for germs: FALSE
  • A German court ruled masks posed a danger to health: FALSE

The Verdict

Public health organisations around the world have recommended the use of face masks in certain settings during the Covid-19 pandemic because of the protection they offer against the spread of infection.

Scientific studies have tested the efficacy of face coverings, including cloth masks.

The suggestion that no study has been done on the protective value of dirty or contaminated cloth masks is a fallacy – official guidance advises that cloth masks should be washed and decontaminated between uses.

There have been multiple studies looking at the effectiveness of cloth masks against viruses, and specifically against Covid-19, and how to clean them.

Current evidence shows that cloth masks are useful in a community setting to prevent the spread of infection, but that medical and surgical masks are more appropriate for healthcare workers, although cloth masks can also be useful in a healthcare setting where other masks are not available.

Many researchers agree that more studies should continue to be carried out to obtain as much information as possible about the best materials, fittings and other properties for cloth masks.

As a result, we rate the claim that masks don’t work: FALSE.

As per our verdict guide, this means: The claim is inaccurate.

TheJournal.ie’s FactCheck is a signatory to the International Fact-Checking Network’s Code of Principles. You can read it here. For information on how FactCheck works, what the verdicts mean, and how you can take part, check out our Reader’s Guide here. You can read about the team of editors and reporters who work on the factchecks here.

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